Length measurement by a two-colour interferometer using two close wavelengths to reduce errors caused by air turbulence

摘要

an improved two-colour interferometer for length measurements was developed to reduce both the errors caused by air turbulence and the effects of chromatic aberration in the optical system. The method combines a fringe-counting technique and a phase-measurement technique. The phases of interference fringes with respect to laser wavelength λ1 and synthetic wavelength λs are detected simultaneously by only one detector by using a band-pass filter technique.